All installed very easily, apart from the right-hand recovery point, and the reason for this is that I cannot seem to find any bolts that fit the stock recovery point threads in the chassis. From what I've been able to ascertain, it's a 14mm bolt. But I've tried all thread pitches and have not been able to get a bolt to fit...

Most people I've spoken to used their stock recovery point bolts. I, unfortunately, don't have that luxury as I don't have them...

Does anybody know what the bolt specifications are ? (ie: Bolt size and thread-pitch)

Alternatively, does anybody have a set of three unused recovery point bolts lying around ?

But if there hasn't been anything in those holes for many years, then the thread can be very dirty, preventing a bolt from going in.

You can try two things:
1) see if you can hire a tap.
2) modify a bolt into a "temporary tap". Cut a groove into a bolt with a cutting blade on an angle grinder, going against the direction of turning, if possible harden it, and use it slowly and with lots of oil.